Fix ghosting on pages following images in grayscale (#2226)

lib/Epub/Epub/blocks/ImageBlock.cpp

@@ -104,6 +104,16 @@ void ImageBlock::render(GfxRenderer& renderer, const int x, const int y) {
     return;
   }
 
+  // Tiled grayscale (#2190): skip the whole image when it doesn't touch the
+  // active band. The per-pixel writer already clips off-band pixels, but without
+  // this each of the ~7 bands per plane re-ran the full cache load / pixel walk
+  // and discarded the result — the dominant cost of AA on image pages. The check
+  // is orientation-aware and returns true when no strip is active, so the BW
+  // pass and non-tiled controllers render the image exactly as before.
+  if (!renderer.glyphIntersectsStrip(x, y, x + width - 1, y + height - 1)) {
+    return;
+  }
+
   // Try to render from cache first
   std::string cachePath = getCachePath(imagePath);
   if (renderFromCache(renderer, cachePath, x, y, width, height)) {

src/activities/reader/EpubReaderActivity.cpp

@@ -940,7 +940,13 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
     } else {
       renderer.displayBuffer(HalDisplay::HALF_REFRESH);
     }
-    // Double FAST_REFRESH handles ghosting for image pages; don't count toward full refresh cadence
+    // The image's own page is handled above and doesn't count toward the full
+    // refresh cadence. But the grayscale pass below leaves gray charge in the
+    // image region that a plain fast diff on the *next* page can't clear, so
+    // text there ghosts gray (#2190). Force the next ordinary page onto the
+    // HALF ghost-cleanup path, which drives every pixel to its target
+    // regardless of residue.
+    pagesUntilFullRefresh = 1;
   } else {
     ReaderUtils::displayWithRefreshCycle(renderer, pagesUntilFullRefresh);
   }